We have used our garage for a guest room quite a lot. It is the best for having a multi-use space.
First thing was the bed set-up. We use a trundle that has 2 singles that nest when not being used.
Others have added a murphy bed. Typical factory options included a set of wall mounted bench/bunks, a drop-down queen bed/bench, or an in wall murphy bed.
You can see the second piece of making the space comfortable in the photo - flooring. We got a nice carpet remanent at the hardware store - cheap. Cut to fit and it can be rolled-up if needed.
The final part of the conversion is temperature control. The garage is often at the end of the aircon and furnace lines and can be hard to manage like the rest of the RV, so we use a small electric space heater and portable aircon just for the garage as needed.
It works very well for an extra room, just like in a house. To us, most RV's are designed for an adult couple or small family that share most all of the RV. We have need for separate space, and the Toy Hauler gives us exactly what we need.
See:
http://www.irv2.com/forums/f49/damon...ml#post1804895
Best luck